In an attempt to delineate the pathophysiology of the shock-lung syndrome, we plan to study the effect of hemorrhagic shock and resuscitation, over a two day period, on the integrity of the pulmonary microcirculation. We will use lung lymph flow and lymph protein transport as indices of fluid filtration and vascular permeability to protein. The adult sheep appears to be ideally suited for this study because we can obtain relatively pure lung lymph and because the sheep lung is similar to that of man both morphologically and in its response to hemorrhagic shock.